The species of pear sucker, also called pear psylla or pear psyllid, which are destructive insects belonging to the genus Cacopsylla (Hemiptera: Psyllidae) cause substantial damage to pear tree plantations. Two consecutive years of research were conducted on the population structure and biological cycle of psylla in a small, elderly, and unmaintained pear orchard in northern Romania. Of the two identified species (C. pyri L. and C. pyricola Forster), C. pyri dominated the psylla population with a percentage of 77.8-80.1%. Adults of both species emerge from hibernation in the first part of March and produce three generations per year. First-generation adults emerge in the first decade of June, the second generation in the last decade of July, and the third generation in the first decade of September as they enter the hibernation phase. Larvae of the first generation appear in the second half of April, the second generation at the end of June - the beginning of July, and the third generation in the second decade of August. There have been reports of up to 11 adults and 27 larvae per leaf, 9 larvae per petiole, and 14 larvae per fruit. The number of adults captured on yellow sticky traps exposed on the southern side of the tree crown was significantly higher compared to the northern side. Following the intense attack, the well-known cv. ‘Williams’ was heavily affected, pear trees were badly defoliated, blackened, and aged prematurely. The climatic conditions of the two years did not influence the phenology of the pests, but the importance of monitoring psyllids is widely argued, considering that it remains the key to integrated protection programs in pear orchards.